When a plurality of applications exist in one system, the applications may be able to be simultaneously executed. However from the viewpoint of a user, the number of the applications the user can simultaneously execute may be extremely small, in most cases, one. Particularly when operations by speech interaction are executed, the number of applications simultaneously interacting with the user is preferably limited to one.
On the other hand, when the user desires to operate an application other than the application currently interacting with the user, the user in a speech interactive system may speak a global command corresponding to a user-desired application. Then the system transfers to a state of interaction between the user and the user-desired application, and to a state of execution of a specific function. It is therefore important for the user's satisfaction that the user is able to directly operate the user-desired application by means of speech without using a textual menu each time to select the user-desired application.
One background interaction type user interface unit detects that a content of a user's speech corresponds to an application other than one being currently executed, and executes the speech interaction application corresponding to the speech content instead of the currently interacting one. (for example, see JP-A No. 56694/2001).
Car navigation systems may be sold by their manufacturers in the form that all programs to be executed in the system are previously installed in the system. In this case, all applications are known to the manufacturer, and thus any state of the system could be anticipated and adjusted to execute normal interaction.
Current speech recognition systems (e.g. car navigation system)are not perfect, for example, a recognition ratio may be decrease as the number of commands to be recognized is increased. As one example, when terminal functions are advanced and more applications are installed, the number of the commands to be managed is greatly increased. Then, the increased command vocabulary may lowers the recognition ratio.
Car navigation systems where applications can be installed from the Internet via mobile phones are possible. In this case, which types of applications that are installed within a system at any given time may not be assumed. Therefore, global commands to be recognized cannot be optimally set according to all the possible states of the navigation system by previously counting the states, for example, the number of the commands to be managed cannot be decreased by adjusting the applications.